This invention relates to an axial split-pin tumbler-type lock, more particularly, a tamper-resistant lock, and a key therefor.
Heretofore, various locks of the axial split-pin tumbler-type have been devised, having means designed to render them tamper- or pick-resistant. Also, lock keys have been designed together with their locks to render the keys difficult to duplicate. The prior locks and keys have achieved varying degrees of success in preventing or forestalling the opening of the locks by unauthorized persons. Generally speaking, it is possible ultimately to pick any key-operated lock, and efforts to prevent unauthorized picking are based on rendering the operation difficult and time-consuming, and also, making it difficult to design a successful pick. In some instances, duplication of keys has been restricted by key designs that are not readily reproduced with conventional equipment, such as used by locksmiths, but, instead, require specialized equipment.
Locks and keys designed to achieve the foregoing objectives are disclosed in U.S. Pat. Nos. 3,267,706, 3,320,783 and 3,813,906. While very useful, the lock and key combinations of these patents, in common with other prior structures, have a rotatable operating part which is constructed so that it lends itself to engagement by a picking tool, in such a manner that torque may be applied to the operating part while the tumblers are being probed.